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Books > Science & Mathematics > Physics > Applied physics & special topics > Astrophysics
Albert Einstein's General Theory of Relativity, published in 1915, made a remarkable prediction: gravitational radiation. Just like light (electromagnetic radiation), gravity could travel through space as a wave and affect any objects it encounters by alternately compressing and expanding them. However, there was a problem. The force of gravity is around a trillion, trillion, trillion times weaker than electromagnetism so the calculated compressions and expansions were incredibly small, even for gravity waves resulting from a catastrophic astrophysical event such as a supernova explosion in our own galaxy. Discouraged by this result, physicists and astronomers didn't even try to detect these tiny, tiny effects for over 50 years. Then, in the late 1960s and early 1970s, two events occurred which started the hunt for gravity waves in earnest. The first was a report of direct detection of gravity waves thousands of times stronger than even the most optimistic calculation. Though ultimately proved wrong, this result started scientists thinking about what instrumentation might be necessary to detect these waves. The second was an actual, though indirect, detection of gravitational radiation due to the effects it had on the period of rotation of two 'neutron stars' orbiting each other. In this case, the observations were in exact accord with predictions from Einstein's theory, which confirmed that a direct search might ultimately be successful. Nevertheless, it took another 40 years of development of successively more sensitive detectors before the first real direct effects were observed in 2015, 100 years after gravitational waves were first predicted. This is the story of that hunt, and the insight it is producing into an array of topics in modern science, from the creation of the chemical elements to insights into the properties of gravity itself.
This volume documents the contributions presented at the Seventh Scientific Meeting of the Spanish Astronomical Society (Sociedad Espanola de Astronomia, SEA). The event bought together 301 participants who presented 161 contributed talks and 120 posters, the greatest numbers up to now. The fact that most exciting items of the current astronomical research were addressed in the meeting proofs the good health of the SEA, a consolidated organization founded fifteen years ago in Barcelona. Two plenary sessions of the meeting were devoted to the approved entrance of Spain as a full member of the European Southern Observatory (ESO) and to the imminent first light of the greatest telescope in the world, the GTC (Gran Telescopio de Canarias), milestones that will certainly lead the Spanish Astronomy in the next future."
Astronomical jets are key astrophysical phenomena observed in gamma-ray bursts, active galactic nuclei or young stars. Research on them has largely occurred within the domains of astronomical observations, astrophysical modeling and numerical simulations, but the recent advent of high energy density facilities has added experimental control to jet studies. Front-line research on jet launching and collimation requires a highly interdisciplinary approach and an elevated level of sophistication. Bridging the gaps between pure magnetohydrodynamics, thermo-chemical evolution, high angular resolution spectro-imaging and laboratory experiments is no small matter. This volume strives to bridge those very gaps. It offers a series of lectures which, taken as whole, act as a thorough reference for the foundations of this discipline. These lectures address the following: - laboratory jets physics from laser and z-pinch plasma
experiments, In addition to the lectures, the book offers, in closing, a
presentation of a series of observational diagnostics, thus
allowing for the recovery of basic physical quantities from jet
emission lines.
This book provides an introduction to the physics of interstellar gas in the Galaxy. It deals with the diffuse interstellar medium which supplies a complex environment for exploring the neutral gas content of a galaxy like the Milky Way and the techniques necessary for studying this non-stellar component. After an initial exposition of the phases of the interstellar medium and the role of gas in a spiral galaxy, the authors discuss the transition from atomic to molecular gas. They then consider basic radiative transfer and molecular spectroscopy with particular emphasis on the molecules useful for studying low-density molecular gas. Observational techniques for investigating the gas and the dust component of the diffuse interstellar medium throughout the electromagnetic spectrum are explored emphasizing results from the recent Herschel and Planck missions. A brief exposition on dust in the diffuse interstellar medium is followed by a discussion of molecular clouds in general and high-latitude molecular clouds in particular. Ways of calibrating CO observations with the molecular hydrogen content of a cloud are examined along with the dark molecular gas controversy. High-latitude molecular clouds are considered in detail as vehicles for applying the techniques developed in the book. Given the transient nature of diffuse and translucent molecular clouds, the role of turbulence in the origin and dynamics of these objects is examined in some detail. The book is targeted at graduate students or postdocs who are entering the field of interstellar medium studies.
This thesis makes two important contributions to plasma physics. The first is the extension of the seminal theoretical works of Spitzer and Braginskii, which describe the basics of particle interactions in plasma, to relativistic systems. Relativistic plasmas have long been studied in high-energy astrophysics and are becoming increasingly attainable in the laboratory. The second is the design of a new class of photon-photon collider, which is the first capable of detecting the Breit-Wheeler process. Though it offers the simplest way for light to be converted into matter, the process has never been detected in the 80 years since its theoretical prediction. The experimental scheme proposed here exploits the radiation used in inertial confinement fusion experiments and could in principle be implemented in one of several current-generation facilities.
The thesis represents the development of an entirely new experimental platform for generating and studying converging radiative shock waves. It was discovered that the application of large magnetic pressures to gas-filled cylindrical metallic tubes could sequentially produce three shocks within the gas. A comprehensive set of instrumentation was devised to explore this system in detail and an exceptionally thorough experimental and theoretical study was carried out in order to understand the source of the shock waves and their dynamics. The research is directed towards some of the most interesting topics in high energy density physics (HEDP) today, namely the interaction of HED material with radiation and magnetic fields, with broad applications to inertial confinement fusion (ICF) and laboratory plasma astrophysics. The work has already generated significant international interest in these two distinct research areas and the results could have significant importance for magnetic ICF concepts being explored at Sandia National Laboratories in the US and for our understanding of the very strong shock waves that are ubiquitous in astrophysics.
The Workshop "Science with the VLT in the ELT Era" held in Garching from 8th to 12th October 2007 was organised by ESO, with support from its Scienti c and Technical Committee, to provide a forum for the astronomical community to debate the long term future of ESO's Very Large Telescope (VLT) and its interferometric mode (VLTI). In particular it was considered useful for future planning to evaluate how its science use may evolve over the next decade due to competition and/or synergy with new facilities such as ALMA, JWST and, hopefully, at least one next generation 30-40 m extremely large telescope whose acronym appears in the title to symbolise this wider context. These discussions were also held in the fresh light of the Science Vision recently developed within ASTRONET as the rst step towards a 20 year plan for implementing astronomical facilities-the rst such attempt within Europe. Speci c ideas and proposals for new, second generation VLT/I instruments were also solicited following a tradition set by several earlier Workshops held since the start of the VLT development. The programme consisted of invited talks and reviews and contributed talks and posters. Almost all those given are included here although, unfortunately not the several lively but constructive discussion sessions.
This prize-winning Ph.D. thesis by Chris Harrison adopts a multi-faceted approach to address the lack of decisive observational evidence, utilising large observational data sets from several world-leading telescopes. Developing several novel observational techniques, Harrison demonstrated that energetic winds driven by Active Galactic Nuclei (AGN) are found in a large number of galaxies, with properties in agreement with model predictions. One of the key unsolved problems in astrophysics is understanding the influence of AGN, the sites of growing supermassive black holes, on the evolution of galaxies. Leading theoretical models predict that AGN drive energetic winds into galaxies, regulating the formation of stars. However, until now, we have lacked the decisive observational evidence to confirm or refute these key predictions. Careful selection of targets allowed Harrison, to reliably place these detailed observations into the context of the overall galaxy population. However, in disagreement with the model predictions, Harrison showed that AGN have little global effect on star formation in galaxies. Theoretical models are now left with the challenge of explaining these results.
This book presents timely work on the nature of the physical processes underpinning two of the basic characteristics of the gas structure in the innermost region of Active Galactic Nuclei (AGN): ionized outflows and emission line regions. In addition, it describes physics-based methods for estimating the density of the astrophysical plasma surrounding AGN. All numerical computations of the photoionized gas employ the most advanced codes available (CLOUDY and TITAN). Calculations of the radiative transfer are based on the assumption of thermal and ionization equilibrium. Promising preliminary examples of comparison with current observations are included for several individual AGN. All of them suggest that the absorbing/emitting gas should have a density on the order of 1012 cm-3. Future observations will provide more objects to verify these results, and will allow us to put constraints on the launch radius of ionized outflows and therefore on the mass loading and kinetic energy outflow rates. These rates, in turn, are crucial to estimating whether the outflows have a significant feedback impact on star formation and metal enrichment in the interstellar medium of the host galaxy. In closing, the book discusses a representative example of applying powerful photoionization techniques to explain the complex physics of the AGN environment.
The goal of the project presented in this book is to detect neutrinos created by resonant interactions of ultrahigh energy cosmic rays on the CMB photon field filling the Universe. In this pioneering first analysis, the author puts forward much of the analysis framework, including calibrations of the electronic hardware and antenna geometry, as well as the development of algorithms for event reconstruction and data reduction. While only two of the 37 stations planned for the Askaryan Radio Array were used in this assessment of 10 months of data, the analysis was able to exclude neutrino fluxes above 10 PeV with a limit not far from the best current limit set by the IceCube detector, a result which establishes the radio detection technique as the path forward to achieving the massive volumes needed to detect these ultrahigh energy neutrinos.
This exhaustive work sheds new light on unsolved questions in gamma-ray astrophysics. It presents not only a complete introduction to the non-thermal Universe, but also a description of the Imaging Atmospheric Cherenkov technique and the MAGIC telescopes. The Fermi-LAT satellite and the HAWC Observatory are also described, as results from both are included. The physics section of the book is divided into microquasars and pulsar wind nebulae (PWNe), and includes extended overviews of both. In turn, the book discusses constraints on particle acceleration and gamma-ray production in microquasar jets, based on the analyses of MAGIC data on Cygnus X-1, Cygnus X-3 and V404 Cygni. Moreover, it presents the discovery of high-energy gamma-ray emissions from Cygnus X-1, using Fermi-LAT data. The book includes the first joint work between MAGIC, Fermi-LAT and HAWC, and discusses the hypothetical PWN nature of the targets in depth. It reports on a PWN population study that discusses, for the first time, the importance of the surrounding medium for gamma-ray production, and in closing presents technical work on the first Large-Size-Telescope (LST; CTA Collaboration), along with a complete description of the camera.
The years 2012/2013 mark the 50th anniversary of the theoretical prediction that Brown Dwarfs, i.e. degenerate objects which are just not massive enough to sustain stable hydrogen fusion, exist. Some 20 years after their discovery, how Brown Dwarfs form is still one of the main open questions in the theory of star formation. In this volume, the pioneers of Brown Dwarf research review the history of the theoretical prediction and the subsequent discovery of Brown Dwarfs. After an introduction, written by Viki Joergens, reviewing Shiv Kumar's theoretical prediction of the existence of brown dwarfs, Takenori Nakano reviews his and Hayashi's calculation of the Hydrogen Burning Minimum Mass. Both predictions happened in the early 1960s. Jill Tarter then writes on the introduction of the term 'Brown Dwarf', before Ben Oppenheimer, Rafael Rebolo and Gibor Basri describe their first discovery of Brown Dwarfs in the 1990s. Lastly, Michael Cushing and Isabelle Baraffe describe the development of the field to the current state of the art. While the book is mainly aimed at the Brown Dwarf research community, the description of the pioneering period in a scientific field will attract general readers interested in astronomy as well.
This book takes the reader for a short journey over the structures of matter showing that their main properties can be obtained even at a quantitative level with a minimum background knowledge including, besides first year calculus and physics, the extensive use of dimensional analysis and the three cornerstones of science, namely the atomic idea, the wave-particle duality and the minimization of energy as the condition for equilibrium. Dimensional analysis employing the universal physical constants and combined with "a little imagination and thinking", to quote Feynman, allow an amazing short-cut derivation of several quantitative results concerning the structures of matter. In the current 2nd edition, new material and more explanations with more detailed derivations were added to make the book more student-friendly. Many multiple-choice questions with the correct answers at the end of the book, solved and unsolved problems make the book also suitable as a textbook. This book is of interest to students of physics, engineering and other science and to researchers in physics, material science, chemistry and engineering who may find stimulating the alternative derivation of several real world results which sometimes seem to pop out the magician's hat.
Several of the very foundations of the cosmological standard model
the baryon asymmetry of the universe, dark matter, and the origin
of the hot big bang itself still call for an explanation from the
perspective of fundamental physics. This workadvocates one
intriguing possibility for a consistent cosmology that fills in the
theoretical gaps while being fully in accordance with the
observational data. At very high energies, the universe might have
been in a false vacuum state that preserved B-L, the difference
between the baryon number B and the lepton number L as a local
symmetry. In this state, the universe experienced a stage of hybrid
inflation that only ended when the false vacuum became unstable and
decayed, in the course of a waterfall transition, into a phase with
spontaneously broken B-L symmetry. This B-L Phase Transition was
accompanied by tachyonic preheating that transferred almost the
entire energy of the false vacuum into a gas of B-L Higgs bosons,
which in turn decayed into heavy Majorana neutrinos. Eventually,
these neutrinos decayed into massless radiation, thereby producing
the entropy of the hot big bang, generating the baryon asymmetry of
the universe via the leptogenesis mechanism and setting the stage
for the production of dark matter. Next to a variety of conceptual
novelties and phenomenological predictions, the main achievement of
the thesis is hence the fascinating notion that the leading role in
the first act of our universe might have actually been played by
neutrinos.
Since the use of high-precision/resolution spectroscopy is closely connected to the ability to collect a large number of photons, the scientific domains using this technique benefit tremendously from the use of 8-meter class telescopes and will fully exploit the tremendous gain provided by future Extremely Large Telescopes (ELTs). This volume comprehensively covers the astrophysical and technical aspects of high-precision spectroscopy with an outlook to future developments.
This book reviews the phenomenology displayed by relativistic jets as well as the most recent theoretical efforts to understand the physical mechanisms at their origin. Relativistic jets have been observed and studied in Active Galactic Nuclei (AGN) for about half a century and are believed to be fueled by accretion onto a supermassive black hole at the center of the host galaxy. Since the first discovery of relativistic jets associated with so-called "micro-quasars" much more recently, it has seemed clear that much of the physics governing the relativistic outflows in stellar X-ray binaries harboring black holes and in AGN must be common, but acting on very different spatial and temporal scales. With new observational and theoretical results piling up every day, this book attempts to synthesize a consistent, unified physical picture of the formation and disruption of jets in accreting black-hole systems. The chapters in this book offer overviews accessible not only to specialists but also to graduate students and astrophysicists working in other areas. Covered topics comprise Relativistic jets in stellar systems Launching of AGN jets Parsec-scale AGN jets Kiloparsec-scale AGN jets Black hole magnetospheres Theory of relativistic jets The structure and dynamics of the inner accretion disk The origin of the jet magnetic field X-ray observations, phenomenology, and connection with theory
Understanding the stars is the bedrock of modern astrophysics. Stars are the source of life. The chemical enrichment of our Milky Way and of the Universe withallelementsheavierthanlithiumoriginatesintheinteriorsofstars.Stars arethe tracersofthe dynamics ofthe Universe,gravitationallyimplying much more than meets the eye. Stars ionize the interstellar medium and re-ionized the early intergalactic medium. Understanding stellar structure and evolution is fundamental. While stellar structure and evolution are understood in general terms, we lack important physical ingredients, despite extensive research during recent decades.Classicalspectroscopy,photometry,astrometryandinterferometryof stars have traditionally been used as observational constraints to deduce the internal stellar physics. Unfortunately, these types of observations only allow the tuning of the basic common physics laws under stellar conditions with relatively poor precision. The situation is even more worrisome for unknown aspects of the physics and dynamics in stars. These are usually dealt with by using parameterised descriptions of, e.g., the treatments of convection, rotation,angularmomentumtransport,theequationofstate,atomicdi?usion andsettlingofelements,magneto-hydrodynamicalprocesses,andmore.There is a dearth of observational constraints on these processes, thus solar values areoftenassignedtothem.Yetitishardtoimaginethatonesetofparameters is appropriate for the vast range of stars.
This book concisely expounds the fundamental concepts, phenomena, theories and procedures in a complete and systematic sense. In this book, not only almost all the important achievements from predecessors but also the contributions from the author himself have been summed up profoundly. Starting from the derivation of fundamental equations, various classical acoustical phenomena such as reflection, refraction, scattering diffraction and absorption in atmosphere, as well as the influences of gravitation and rotation of the earth on the behaviors of different atmospheric waves including acoustic waves, have been discussed in viewpoints of wave acoustics and geometrical acoustics respectively. The recent developments of several computation methods in the field of atmospheric acoustics have been introduced in some detail. As for the application aspects, atmospheric remote sensing has been discussed from the angle of inverse problems.
In early April 1911 Albert Einstein arrived in Prague to become full professor of theoretical physics at the German part of Charles University. It was there, for the first time, that he concentrated primarily on the problem of gravitation. Before he left Prague in July 1912 he had submitted the paper Relativitat und Gravitation: Erwiderung auf eine Bemerkung von M. Abraham in which he remarkably anticipated what a future theory of gravity should look like. At the occasion of the Einstein-in-Prague centenary an international meeting was organized under a title inspired by Einstein's last paper from the Prague period: "Relativity and Gravitation, 100 Years after Einstein in Prague." The main topics of the conference included: classical relativity, numerical relativity, relativistic astrophysics and cosmology, quantum gravity, experimental aspects of gravitation and conceptual and historical issues. The conference attracted over 200 scientists from 31 countries, among them a number of leading experts in the field of general relativity and its applications. This volume includes abstracts of the plenary talks and full texts of contributed talks and articles based on the posters presented at the conference. These describe primarily original results of the authors. Full texts of the plenary talks are included in the volume "General Relativity, Cosmology and Astrophysics--Perspectives 100 Years after Einstein in Prague," eds. J. Bi ak and T. Ledvinka, published also by Springer Verlag."
Mars, the most habitable of our sister planets, holds a special place in our imaginations and in our space exploration program. Fully half of NASA's planetary exploration effort is now devoted to Mars. Key questions include: Has Mars ever harbored life? Is there life on Mars now? Will humans be able to survive on the Martian surface? Answers to these questions lie in determining the present location of water on Mars and its likely inventory in the past, and in determining the present radiation environment of Mars. The 2001 Mars Odyssey Mission contributes greatly these answers by detecting near-surface water through measurements of neutron flux, from the detection of carbonates, and the quantification of its radiation environment. This book captures the objectives, the design of the mission and the details of the instruments carried to Mars. It should be of interest to every scientist interested in participating in the on-going exploration of Mars from graduate students to senior scientists as it provides the background information essential to interpret the many exciting results now appearing from the mission.
It is over a quarter of a century since the discovery of out?ows from young stars. The intervening years have led to remarkable advances in our understanding of this phenomenon. Much of the progress can be attributed to advances in facilities and technologies, including not only larger telescopes but also improved instrument and detector performance. In addition protostellar out?ows have now been imaged from the ground and space at high spatial resolution, e. g. with HST, and at a wide - riety of wavelengths from X-rays to radio waves, revealing more and more about their physics. This veritable revolution in observation has been accompanied by an exponential growth in our ability to numerically simulate the launching and pro- gation of jets. Codes continue to improve: they now incorporate more physics and are increasingly ef?cient through, for example, techniques such as adaptive mesh re?nement and the use of parallel processing in cluster environments. Simulating the launching and propagation of a jet all the way from the vicinity of the star up to 4 several thousand AU (a size range of10 ) is now much closer. In more recent times, developments in observation, theory and numerical s- ulation have been joined by laboratory jet experiments reproducing, on centimetre scales, that which is seen in astrophysics to stretch for several parsecs.
This book deals with the astrophysics and spectroscopy of the interstellar molecules. In the introduction, overview and history of interstellar observations are described in order to help understanding how the modern astrophysics and molecular spectroscopy have been developed interactively. The recent progress in the study of this field is briefly summarized. Furthermore, the basic knowledge of molecular spectroscopy, which is essential to correctly comprehend the astrophysical observations, is presented in a compact form.
This book is a synopsis of modern deep-field astronomy, based on the powerful telescopes and instruments developed in recent years. It is organized along topical themes, such as the extragalactic background radiation at different wavelengths, the evolution of galaxies, the history of star formation, the nature of absorbers, the reionization of the intergalactic medium, the validity of photometric redshifts, gravitational lensing, and clustering of galaxies. Stellar and substellar objects were not neglected, however, and one session was devoted to nearby bodies such as trans-Neptunian solar system objects, brown dwarfs, and stars with special characteristics. |
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